Researchers have discussed publicly a generic MITM (man in the middle) attack against SSL 3.0 and TLS 1.0 connections. These are widely used to provide secure and authenticated connections across networks, including the Internet, and are the basis of HTTPS.

The details of the attack are fairly complicated, but basically an "authentication gap" allows a 3rd party to trick a server into responding to an unauthenticated request in a standards-compliant way. To quote Ray, the attacker may:

...inject a chosen plaintext prefix into the encrypted data stream, often without detection by either end of the connection. This is possible because an "authentication gap" exists during the renegotiation process at which the MitM may splice together disparate TLS connections in a completely standards-compliant way.

It's not clear, at least not to me, how easy an attack this is to mount. Ray identified one, possibly two solutions that could be implemented in SSL/TLS software to prevent it, but he mentioned no workarounds for current implementations. We'll have to wait for more developments to know how immediately serious the problems are.

About the Author

Larry Seltzer has been writing software for and English about computers ever sincemuch to his own amazementhe graduated from the University of Pennsylvania in 1983.
He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find See Full Bio

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